Zend\XmlRpc\Server is composed of a variety of components, ranging from the server itself to request, response,
and fault objects.

To bootstrap Zend\XmlRpc\Server, the developer must attach one or more classes or functions to the server, via
the setClass() and addFunction() methods.

Once done, you may either pass a Zend\XmlRpc\Request object to Zend\XmlRpc\Server::handle(), or it will
instantiate a Zend\XmlRpc\Request\Http object if none is provided – thus grabbing the request from
php://input.

Zend\XmlRpc\Server::handle() then attempts to dispatch to the appropriate handler based on the method
requested. It then returns either a Zend\XmlRpc\Response-based object or a Zend\XmlRpc\Server\Faultobject. These objects both have __toString() methods that create valid XML-RPCXML responses, allowing them
to be directly echoed.

For maximum performance it is recommended to use a simple bootstrap file for the server component. Using
Zend\XmlRpc\Server inside a Zend\Controller is strongly discouraged to avoid the
overhead.

Services change over time and while webservices are generally less change intense as code-native APIs, it is
recommended to version your service. Do so to lay grounds to provide compatibility for clients using older versions
of your service and manage your service lifecycle including deprecation timeframes. To do so just include a version
number into your URI. It is also recommended to include the remote protocol name in the URI to allow easy
integration of upcoming remoting technologies. http://myservice.ws/1.0/XMLRPC/.

Most of the time it is not sensible to expose business objects directly. Business objects are usually small and
under heavy change, because change is cheap in this layer of your application. Once deployed and adopted, web
services are hard to change. Another concern is I/O and latency: the best webservice calls are those not
happening. Therefore service calls need to be more coarse-grained than usual business logic is. Often an additional
layer in front of your business objects makes sense. This layer is sometimes referred to as Remote Facade. Such
a service layer adds a coarse grained interface on top of your business logic and groups verbose operations into
smaller ones.

Zend\XmlRpc\Server allows the developer to attach functions and class method calls as dispatchable XML-RPC
methods. Via Zend\Server\Reflection, it does introspection on all attached methods, using the function and
method docblocks to determine the method help text and method signatures.

XML-RPC types do not necessarily map one-to-one to PHP types. However, the code will do its best to guess the
appropriate type based on the values listed in @param and @return lines. Some XML-RPC types have no immediate
PHP equivalent, however, and should be hinted using the XML-RPC type in the PHPDoc. These include:

PhpDocumentor does no validation of the types specified for params or return values, so this will have no impact on
your API documentation. Providing the hinting is necessary, however, when the server is validating the parameters
provided to the method call.

It is perfectly valid to specify multiple types for both params and return values; the XML-RPC specification even
suggests that system.methodSignature should return an array of all possible method signatures (i.e., all possible
combinations of param and return values). You may do so just as you normally would with PhpDocumentor, using the
‘|’ operator:

XML-RPC has a concept of namespacing; basically, it allows grouping XML-RPC methods by dot-delimited
namespaces. This helps prevent naming collisions between methods served by different classes. As an example, the
XML-RPC server is expected to server several methods in the ‘system’ namespace:

system.listMethods

system.methodHelp

system.methodSignature

Internally, these map to the methods of the same name in Zend\XmlRpc\Server.

If you want to add namespaces to the methods you serve, simply provide a namespace to the appropriate method when
attaching a function or class:

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// All public methods in My_Service_Class will be accessible as// myservice.METHODNAME$server->setClass('My\Service\Class','myservice');// Function 'somefunc' will be accessible as funcs.somefunc$server->addFunction('somefunc','funcs');

Most of the time, you’ll simply use the default request type included with Zend\XmlRpc\Server,
Zend\XmlRpc\Request\Http. However, there may be times when you need XML-RPC to be available via the CLI, a
GUI, or other environment, or want to log incoming requests. To do so, you may create a custom request object
that extends Zend\XmlRpc\Request. The most important thing to remember is to ensure that the getMethod()
and getParams() methods are implemented so that the XML-RPC server can retrieve that information in order to
dispatch the request.

Similar to request objects, Zend\XmlRpc\Server can return custom response objects; by default, a
Zend\XmlRpc\Response\Http object is returned, which sends an appropriate Content-Type HTTP header for use
with XML-RPC. Possible uses of a custom object would be to log responses, or to send responses back to
STDOUT.

To use a custom response class, use Zend\XmlRpc\Server::setResponseClass() prior to calling handle().

Zend\XmlRpc\Server catches Exceptions generated by a dispatched method, and generates an XML-RPC fault
response when such an exception is caught. By default, however, the exception messages and codes are not used in a
fault response. This is an intentional decision to protect your code; many exceptions expose more information about
the code or environment than a developer would necessarily intend (a prime example includes database abstraction or
access layer exceptions).

Exception classes can be whitelisted to be used as fault responses, however. To do so, simply utilize
Zend\XmlRpc\Server\Fault::attachFaultException() to pass an exception class to whitelist:

If you utilize an exception class that your other project exceptions inherit, you can then whitelist a whole family
of exceptions at a time. Zend\XmlRpc\Server\Exceptions are always whitelisted, to allow reporting specific
internal errors (undefined methods, etc.).

Any exception not specifically whitelisted will generate a fault response with a code of ‘404’ and a message of
‘Unknown error’.

Attaching many classes to an XML-RPC server instance can utilize a lot of resources; each class must introspect
using the Reflection API (via Zend\Server\Reflection), which in turn generates a list of all possible method
signatures to provide to the server class.

To reduce this performance hit somewhat, Zend\XmlRpc\Server\Cache can be used to cache the server definition
between requests. When combined with __autoload(), this can greatly increase performance.

The above example attempts to retrieve a server definition from xmlrpc.cache in the same directory as the
script. If unsuccessful, it loads the service classes it needs, attaches them to the server instance, and then
attempts to create a new cache file with the server definition.

The arguments passed at setClass() at server construction time are injected into the method call
pricing.calculate() on remote invokation. In the example above, only the argument $purchaseId is expected
from the client.

Passing arguments only to constructor

Zend\XmlRpc\Server allows to restrict argument passing to constructors only. This can be used for constructor
dependency injection. To limit injection to constructors, call sendArgumentsToAllMethods and pass FALSE as
an argument. This disables the default behavior of all arguments being injected into the remote method. In the
example below the instance of ProductRepository and PurchaseRepository is only injected into the
constructor of Services_PricingService2.

setClass() allows to register a previously instantiated class at the server. Just pass an instance instead of
the class name. Obviously passing arguments to the constructor is not possible with pre-instantiated classes.

Attaching several classes using namespaces

The example below illustrates attaching several classes, each with their own namespace.

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require_once'Services/Comb.php';require_once'Services/Brush.php';require_once'Services/Pick.php';$server=newZend\XmlRpc\Server();$server->setClass('Services\Comb','comb');// methods called as comb.*$server->setClass('Services\Brush','brush');// methods called as brush.*$server->setClass('Services\Pick','pick');// methods called as pick.*echo$server->handle();

Specifying exceptions to use as valid fault responses

The example below allows any Services\Exception-derived class to report its code and message in the fault
response.

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require_once'Services/Exception.php';require_once'Services/Comb.php';require_once'Services/Brush.php';require_once'Services/Pick.php';// Allow Services_Exceptions to report as fault responsesZend\XmlRpc\Server\Fault::attachFaultException('Services\Exception');$server=newZend\XmlRpc\Server();$server->setClass('Services\Comb','comb');// methods called as comb.*$server->setClass('Services\Brush','brush');// methods called as brush.*$server->setClass('Services\Pick','pick');// methods called as pick.*echo$server->handle();

Utilizing custom request and response objects

Some use cases require to utilize a custom request object. For example, XML/RPC is not bound to HTTP as a
transfer protocol. It is possible to use other transfer protocols like SSH or telnet to send the request and
response data over the wire. Another use case is authentication and authorization. In case of a different transfer
protocol, one need to change the implementation to read request data.

The example below instantiates a custom request class and passes it to the server to handle.

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require_once'Services/Request.php';require_once'Services/Exception.php';require_once'Services/Comb.php';require_once'Services/Brush.php';require_once'Services/Pick.php';// Allow Services_Exceptions to report as fault responsesZend\XmlRpc\Server\Fault::attachFaultException('Services\Exception');$server=newZend\XmlRpc\Server();$server->setClass('Services\Comb','comb');// methods called as comb.*$server->setClass('Services\Brush','brush');// methods called as brush.*$server->setClass('Services\Pick','pick');// methods called as pick.*// Create a request object$request=newServices\Request();echo$server->handle($request);

Specifying a custom response class

The example below illustrates specifying a custom response class for the returned response.

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require_once'Services/Request.php';require_once'Services/Response.php';require_once'Services/Exception.php';require_once'Services/Comb.php';require_once'Services/Brush.php';require_once'Services/Pick.php';// Allow Services_Exceptions to report as fault responsesZend\XmlRpc\Server\Fault::attachFaultException('Services\Exception');$server=newZend\XmlRpc\Server();$server->setClass('Services\Comb','comb');// methods called as comb.*$server->setClass('Services\Brush','brush');// methods called as brush.*$server->setClass('Services\Pick','pick');// methods called as pick.*// Create a request object$request=newServices\Request();// Utilize a custom response$server->setResponseClass('Services\Response');echo$server->handle($request);

useZend\XmlRpc\ServerasXmlRpcServer;// Register the "Services" namespace$loader=newZend\Loader\StandardAutoloader();$loader->registerNamespace('Services','path to Services');$loader->register();// Specify a cache file$cacheFile=dirname(__FILE__).'/xmlrpc.cache';// Allow Services\Exceptions to report as fault responsesXmlRpcServer\Fault::attachFaultException('Services\Exception');$server=newXmlRpcServer();// Attempt to retrieve server definition from cacheif(!XmlRpcServer\Cache::get($cacheFile,$server)){$server->setClass('Services\Comb','comb');// methods called as comb.*$server->setClass('Services\Brush','brush');// methods called as brush.*$server->setClass('Services\Pick','pick');// methods called as pick.*// Save cacheXmlRpcServer\Cache::save($cacheFile,$server);}// Create a request object$request=newServices\Request();// Utilize a custom response$server->setResponseClass('Services\Response');echo$server->handle($request);

Note

The server cache file should be located outside the document root.

Optimizing XML generation

Zend\XmlRpc\Server uses DOMDocument of PHP extension ext/dom to generate it’s XML output. While
ext/dom is available on a lot of hosts it is not exactly the fastest. Benchmarks have shown, that XmlWriter
from ext/xmlwriter performs better.

If ext/xmlwriter is available on your host, you can select a the XmlWriter-based generator to leverage the
performance differences.

Performance is determined by a lot of parameters and benchmarks only apply for the specific test case.
Differences come from PHP version, installed extensions, webserver and operating system just to name a few.
Please make sure to benchmark your application on your own and decide which generator to use based on your
numbers.

Note

Benchmark your client

This optimization makes sense for the client side too. Just select the alternate XML generator before doing
any work with Zend\XmlRpc\Client.